A method for the production of window elements which can be soldered in a hermetically tight manner in which stray light or interference radiation is prevented from penetrating through the arrangement of an improved adherence layer system with barrier layer and interdiffusion layer is known in the prior art from DE 10 2005 024 512 B3. The window elements which are produced result from frame-shaped partial regions which are easy to work with because of their rectangular shape, but are limited with respect to their limiting of the beam width angle in minimized-surface sensors or detectors. Accordingly, in case of area sensors or image detectors having small dimensions, the window elements produced in this way result in limitations as regards adapting to the existing housing and in loss of quality.
Further, DE 10 2007 039 291 A1 discloses an optoelectronic semiconductor module which is outfitted with a light-emitting semiconductor chip mounted on a chip carrier, with a cover element having an at least partially permeable cover plate over the semiconductor chip, and with a frame part for laterally enclosing the semiconductor chip. The cover plate and frame part are connected to one another by anodic bonding without a joining layer. The frame part and chip carrier can be then be connected like conventional metal chip carriers and caps by soldering.
Further, it is also known to produce circular window elements individually and to glue these circular window elements into a housing according to their intended purpose.
However, a disadvantage consists in the related handling expenditure for individual fabrication and the limitation with respect to window size. Therefore, individual fabrication of area sensors, image detectors and endoscopes of small dimensions (1-5 mm) is very laborious and a method of this kind is accordingly unsuitable for series production. In addition, these elements are extremely prone to malfunction and are therefore also cost-intensive. Further, in the case of glued window elements the permeability (gas permeability) of the glue has a negative impact on the long-term stability of systems on this basis which require a 100-percent hermetically gastight (vacuum-compliance) joint. Only quasi-hermetic joints can be produced with glued windows. In contrast, hermetically gastight, temperature-resistant systems with long-term stability can be constructed with soldered window elements.